Moving from a linear rewards curve to a convergent linear rewards curve.
Inevitably, large accounts that game the system with the current linear reward curve would come up with innovative ways to game the system with a convergent linear rewards curve.
Maybe, but the idea is to make it more profitable to vote honestly and less profitable to self vote or sell votes. So there are less overall incentives to game the system.
Just because every set of economic rules can be taken exploited on some level (this isn't technically true, but lets assume it is) doesn't mean they're all equal. Some are just better than others at promoting a certain behavior, in this case, people to vote relatively honestly.